This list compiled by user luis.oliveira might help see the big picture. It helped me. http://duolingo.com/#/comment/266283?from_skill=52dd6771aa26cd460a4643af352e694f
In the US, and probably other English speaking countries, people will understand "y'all" or "you guys" and might even understand "youze" or "yuz." But they are all non-standard, aren't considered "proper English" and might be perceived negatively, especially in a formal setting.
It might be acceptable to use some of these in casual usage, but only in areas where they are in use. But some are best avoided even in areas where they are used.
"All of you" might be your best option.
Your guy's eyes didn't work, but I guess it doesn't really make that much sense in English..